Looking at the aircraft built in the past 10years, how much/percentage can be re-used in other aircraft once its time is over, is the airline industry "user friendly" to the environment in this respect?

I would say that spare parts are sold to companies that stock spares. The rest wold probabaly melted down and used for other purposes....As for parts that cannot be used for spares, you would have to consult an aluminum scapr dealer to find out the specifics...

Quoting Readytotaxi (Thread starter):Looking at the aircraft built in the past 10years, how much/percentage can be re-used in other aircraft once its time is over, is the airline industry "user friendly" to the environment in this respect?

Removable parts in good condition would go back into the spares pool if a market exists. This is a path of diminishing returns though since, as fleets age, spares demand for several types of common LRU's shrinks.

Much of the structure would go for scrap. Whole pieces can be used for structural spares, but the demand for that type of part isn't all that high. Most OEM's won't recycle aircraft structural metal into new aircraft sturcture for quality control reasons, but it can go back into the recycling pipeline for other things (a lot of soda cans are probably old airliners).